This application claims the priority of German patent document 198 55 439.7, filed Nov. 27, 1998, the disclosure of which is expressly incorporated by reference herein.
The invention relates to a d.c. converter which operates according to the switch controller principle.
D.C. converters of this type generate alternating currents to of undesirable high frequencies, which are superimposed on the received direct current. In order to protect an input direct voltage source from such interference, a filter consisting of chokes and capacitors must be connected between it and the direct current converter. As the result of the good attenuation of multistage L-C filters, the interference currents can be attenuated to acceptable values for the feeding source.
In all applications, and particularly when used in aviation and space operations, such voluminous chokes and capacitors are undesirable because they increase the size, and especially the weight, of the power supply systems.
It is an object of the invention to provide a choke which is small and light weight, without changing the characteristic attenuation curve of the filter to such an extent that the effective protection against high-frequency interferences is lost.
This and other objects and advantages are achieved by the filter for a D.C. voltage converter according to the invention, which includes chokes L1, L2 and capacitors C1, C21. The filter is connected between the feeding source and the direct voltage converter, and an auxiliary alternating voltage source U.sub.H connected in series with the capacitor C1 has the same alternating voltage amplitude as the interference voltage U.sub.C1 at 180.degree. phase angle rotation.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.